Multi-spectral planar photodiode infrared radiation detector pixels

Abstract

Multi-spectral planar photodiode pixels are provided in accordance with the present invention for simultaneously detecting multi-colors of infrared radiation. Each multispectral planar photodiode pixel includes a semiconductor substrate layer, a buffer layer of a first conductivity type material deposited on a semiconductor substrate layer, and a first color layer of the first conductivity type material deposited on the buffer layer. The multispectral planar photodiode pixel further includes a barrier layer of the first conductivity type material deposited on the first color layer, a second color layer of the first conductivity type material deposited on the barrier layer, and a cap layer of the first conductivity type material deposited on the second color layer. A first diode comprising a second conductivity type material is formed in the first color layer, and a second diode comprising a second conductivity type material is formed in the second layer.

We claim: 
     
       1. A radiation detector for detecting electromagnetic radiation at a plurality of spectral bands, comprising: a multi-layered semiconductor structure comprising a plurality of layers, wherein each of the layers of the multi-layered semiconductor structure comprises a first conductivity type;   a first planar diode deposited in a first color layer of the multi-layered semiconductor structure, the first planar diode intersecting only a portion of a planar surface area of the first color layer, the first color layer having a first band gap and the first planar diode having a second conductivity type; and   an additional planar diode deposited in an additional color layer of the multi-layered semiconductor structure, the additional color layer having an additional band gap and the additional planar diode having the second conductivity type, the first band gap being greater than the second band gap and the additional planar diode intersecting only a portion of a planar surface area of the additional color layer.   
     
     
       2. The radiation detector as set forth in claim 1, wherein the multi-layered semiconductor structure comprises a 5 layer epitaxial structure which is grown by molecular beam epitaxy. 
     
     
       3. The radiation detector as set forth in claim 2, wherein the multi-layered semiconductor structure comprises a multi-layered p-type semiconductor structure. 
     
     
       4. The radiation detector as set forth in claim 2, and further including a delineating trench formed around the two planar diodes. 
     
     
       5. The radiation detector as set forth in claim 4, wherein: the delineating trench is etched into the five layers; and   a conductor is formed within the delineating trench.   
     
     
       6. The radiation detector as set forth in claim 1, wherein the multi-layered semiconductor structure comprises a multi-layered n-type semiconductor structure. 
     
     
       7. The radiation detector as set forth in claim 6, wherein the multi-layered n-type semiconductor structure comprises a 5 layer epitaxial structure which is grown by molecular beam epitaxy. 
     
     
       8. The multi-color pixel as set forth in claim 1, wherein The multi-layered semiconductor structure is generated by growing the layers of the multi-layered semiconductor structure in a single growth run. 
     
     
       9. The radiation detector as set forth in claim 1, and further comprising: at least one other planar diode deposited in at least one other color layer of the multi-layered semiconductor structure, the at least one other color layer having at least one other band gap and the at least one other planar diode having the second conductivity type, the first band gap being greater than the second band gap and the at least one other planar diode intersecting only a portion of a planar surface area of the at least one other color layer.   
     
     
       10. A multi-color pixel comprising: a semiconductor substrate layer;   a buffer layer of a first conductivity type material deposited on the semiconductor substrate layer;   a first color layer of the first conductivity type material deposited on the buffer layer;   a barrier layer of the first conductivity type material deposited on the first color layer;   a second color layer of a first conductivity type material deposited on the barrier layer; and   a cap layer of a first conductivity type material deposited on the second color layer;   wherein a first planar diode comprising a second conductivity type material is formed in a portion of a planar surface area of first color layer; and   wherein a second planar diode comprising a second conductivity type material is formed in a portion of a planar surface area of the second color layer.   
     
     
       11. The multi-color pixel as set forth in claim 10, wherein the first buffer layer, the first color layer, the barrier layer, the second color layer, and the cap layer are deposited on the semiconductor substrate in a single growth run. 
     
     
       12. The multi-color pixel as set forth in claim 10, and further including a delineating trench formed around the first and second planar diodes. 
     
     
       13. The multi-color pixel as set forth in claim 12, wherein a conductor is formed within the delineating trench. 
     
     
       14. The multi-color pixel as set forth in claim 10, wherein the first-conductivity type material comprises a p-type material. 
     
     
       15. The multi-color pixel as set forth in claim 14, wherein the semiconductor substrate comprises a CdZnTe semiconductor substrate;   the first color layer comprises a HgCdTe semiconductor structure having a first band gap; and   the second color comprises a HgCdTe semiconductor structure having a second band gap.   
     
     
       16. The multi-color pixel as set forth in claim 15, wherein the first band gap is greater than the second band gap. 
     
     
       17. The multi-color pixel as set forth in claim 10, wherein the first-conductivity type material comprises an n-type material. 
     
     
       18. The multi-color pixel as set forth in claim 17, wherein the semiconductor substrate comprises a CdZnTe semiconductor substrate;   the first color layer comprises a HgCdTe semiconductor structure having a first band gap; and   the second color layer comprises a HgCdTe semiconductor structure having a second band gap.   
     
     
       19. The multi-color pixel as set forth in claim 18, wherein the first band gap is greater than the second band gap.